If such chain saws are utilized in cold weather, there is the danger that the moisture drawn in with the cold air condenses in the region of the air intake channel and especially on the throttle flap of the carburetor to form ice on the throttle flap. During idle, the engine will run unevenly as a consequence of this icing condition. This can cause the engine to come to an unwanted standstill thereby disrupting work being conducted with the chain saw. On the other hand, the idle speed of the engine can suddenly increase so far that the centrifugal clutch engages and the saw chain is suddenly and unexpectly set in motion and this can cause work accidents. Furthermore, icing of the carburetor can cause the maximum permissible speed of the engine and the permissible temperature to become exceeded which causes premature wear.
In known chain saws, these dangers and disadvantages are prevented by returning a portion of the heated air given off by the engine to prewarm the air inducted into the engine; however, other disadvantages must then be accepted. The inducted air heated by the engine entrains additional moisture and dirt during operation and sometimes snow so that operating disturbances can again occur and an increased maintenance effort with respect to the cleaning of the filter is then needed. Also, a substantial constructive effort is necessary for feeding the warm air back into the air intake channel.